I have had terrible trouble with 7.4.2 and 8.1.0 on a Dell XPS9360. Whether booting from the KNOPPIX DVD (burn iso) or from a boot USB (I use Pendrive's Universal-USB-Installer v., there may be other or later versions) all I got was a blank screen. But a certain amount of whirring suggested to me that the live version was in fact progressing and available. After a lot of messing about with vga=xxx in the KERNEL stanza in /boot/isolinux/isolinux.cfg I iterated to the best, sparsest and most portable version of this configuration file that I have EVER had. It reads
DEFAULT console
LABEL console
KERNEL linux
APPEND initrd=minirt.gz vga=893 lang=uk 1
LABEL video
KERNEL linux
APPEND initrd=minirt.gz vga=893 lang=uk #

By portable I mean this works on an ancient (really ancient) Samsung, any number of Dells in all configurations / ages, likewise Fujitsus. All screens from 800x600 to 1920x1080.
Still can't get 8.1.0 to work using a boot USB (DVD is fine). The architecture dictated by Pendrive leads to a configuration location error ("Can't find ..") from the very start. Even mimicking the geography of the 7.4.2 boot USB does not mend this.